Narrative:

On takeoff from runway 01 at dca we were assigned the REBLL2 RNAV departure. Prior to takeoff roll; both flight directors had been turned on with the captain's (PF) set as master and LNAV was armed. On takeoff roll; the toga button was depressed and the autothrottles set the commanded takeoff thrust. Sometime between then and 400 feet AGL the flight directors disappeared from view and LNAV failed to engage. This was noticed at 400 feet AGL with the normal procedure to 'verify LNAV.' I (pm) reselected toga to regain the flight directors then selected LNAV. Meanwhile; observing outside the cockpit that we were in danger of proceeding north of the potomac river; I directed a left turn which the captain (PF) was already beginning to initiate. We intercepted the normal departure course and flew the departure as published. By our estimation we had not entered the restricted airspace. I was also monitoring guard frequency and we received no radio communication on that frequency.

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Original NASA ASRS Text

Title: A B737NG departed DCA on the REBLL2 RNAV. Shortly after takeoff both flight directors failed and LNAV ceased guidance so the crew manually initiated a turn to the departure course and avoided P56.

Narrative: On takeoff from Runway 01 at DCA we were assigned the REBLL2 RNAV Departure. Prior to takeoff roll; both flight directors had been turned on with the Captain's (PF) set as master and LNAV was armed. On takeoff roll; the TOGA button was depressed and the autothrottles set the commanded takeoff thrust. Sometime between then and 400 feet AGL the flight directors disappeared from view and LNAV failed to engage. This was noticed at 400 feet AGL with the normal procedure to 'Verify LNAV.' I (PM) reselected TOGA to regain the flight directors then selected LNAV. Meanwhile; observing outside the cockpit that we were in danger of proceeding north of the Potomac River; I directed a left turn which the Captain (PF) was already beginning to initiate. We intercepted the normal departure course and flew the departure as published. By our estimation we had not entered the restricted airspace. I was also monitoring Guard frequency and we received no radio communication on that frequency.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.